Writing instrument



FIG. 1 is a front view of the writing instrument showing my new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a perspective view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a perspective view thereof with the writing tip protruding. 

The ornamental design for a writing instrument, as shown and described. 